Pump device

ABSTRACT

A pump device may include an eccentric member mounted on an output shaft in an eccentric manner, a cam mechanism which is engaged with the eccentric member to convert a motion of the output shaft into a radial direction and at least one pump body which includes a diaphragm that is moved in the radial direction in relation to the output shaft by the cam mechanism for performing a pumping operation.

CROSS REFERENCE TO RELATED APPLICATION

The present invention claims priority under 35 U.S.C. § 119 to Japanese Application No. 2004-166205 filed Jun. 3, 2004, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a pump device for circulating fluid. More specifically, the present invention relates to a pump device provided with a pump body utilizing a diaphragm.

BACKGROUND OF THE INVENTION

A conventional circulating pump 100 has been known in which a plurality of pump bodies 102 are provided for sucking and compressing fluid by means of the operation of diaphragms 101 and the diaphragms 101 of the respective pump bodies 102 are disposed on the same plane as shown in FIG. 26 (see Japanese Patent Laid-Open No. Hei 11-62837). The circulating pump 100 includes a motor 103 as a drive source, a rotation shaft 104 rotated by the motor 103 and provided with an end face slightly inclined with respect to its rotation center, a cam plate 105 rotatably supported on the inclined peripheral surface of the rotation shaft 104, and diaphragms 101 disposed at equal intervals around the cam plate 105.

When the motor 103 is driven continuously and the rotation shaft 104 is rotated, the peripheral part of the cam plate 105 is moved in the axial direction of the rotation shaft 104 by the inclined end face of the rotation shaft 104. The up and down operations of the respective diaphragms 101 are performed by the movement in the axial direction of the cam plate 105. When the diaphragm 101 is pressed, the capacity of a pressure chamber 106 is decreased and fluid is sent in one direction by the operation of an inflow valve and an outflow valve.

However, in the above-mentioned circulating pump 100, the diaphragms 101 are disposed on the same plane and thus downsizing is difficult while maintaining the size of the pump body 102. Further, since the diaphragms 101 are disposed on the same plane, the diameter of the cam plate 105 has to be also enlarged when the diaphragm 101 is enlarged in order to increase the flow rate, and thus an extensive modification is required.

In addition, since the cam plate 105 is slightly inclined with respect to the disposing face of the diaphragm 101 and the motor 103 is continuously rotated, it is difficult to operate only one of the pump bodies 102 at a time. In other words, since the cam plate 105 is slightly inclined with respect to the disposing face of the diaphragm 101, adjacent pump bodies 102 are operated together. Therefore, it is difficult to operate only one of the pump bodies 102 at a time in order to obtain a little flow rate.

SUMMARY OF THE INVENTION

In view of the problems described above, the present invention may advantageously provide a pump device that can be easily miniaturized and can obtain a little flow rate.

Thus, according to an embodiment of the present invention, there may be provided a pump device including a motor, an eccentric member which is mounted on an output shaft of the motor in an eccentric manner, a cam mechanism which engages with the eccentric member and converts into a motion in a radial direction of the output shaft, and a plurality of pump bodies each of which includes a diaphragm that is moved in the radial direction of the output shaft by the cam mechanism for performing a pumping operation.

According to an embodiment of the present invention, when a motor is driven, an eccentric member is rotated and a diaphragm is pressed through a cam mechanism to operate a pump body. Therefore, the pump device is operated and fluid is sucked or compressed.

In the pump device described above, a stepping motor may be preferably used as the motor. When a stepping motor is used, the cam mechanism may be controlled by a small angle, and at this time, only one of the plurality of pump bodies can be operated to obtain a little flow rate.

In accordance with an embodiment of the present invention, the cam mechanism may preferably include a contact ring which is rotatably mounted with respect to the eccentric member and, when the eccentric member is rotated, the contact ring makes the diaphragm move in the radial direction of the output shaft while the contact ring relatively rotates with respect to the eccentric member. When the cam mechanism is constructed such that the contact ring makes the diaphragm move in the radial direction while the contact ring is relatively rotated with respect to the eccentric member, the contact ring does not perform the operation of pushing while rotating with respect to the diaphragm and thus the movement of the diaphragm in the radial direction can be stably performed.

In accordance with an embodiment of the present invention, a pressure chamber may be provided which is closed by the diaphragm and is in communication with an inflow passage and an outflow passage and a projecting part for moving the diaphragm is formed on an opposite side to the pressure chamber with respect to the diaphragm. According to the construction described above, when the pressure of the pressure chamber increases with the diaphragm being pushed by the contact ring through the projecting part, fluid flows out from the pressure chamber and, when the diaphragm is returned, the pressure of the pressure chamber decreases to make fluid flow into the pressure chamber.

In accordance with an embodiment of the present invention, the projecting part of the diaphragm may be preferably covered with a fluorine coating or material having an abrasion resistance property and a low friction coefficient for the improvement of durability and the reduction of contact resistance.

In accordance with an embodiment of the present invention, a plurality of pump bodies may be four pump bodies which are disposed around the cam mechanism at every 90 degrees with an equal distance, and only one of the four pump bodies is preferably operated by the contact ring at a time. When only one of the four pump bodies can be operated by the contact ring at a time, an output with a little flow rate can be easily obtained.

In accordance with an embodiment of the present invention, the cam mechanism may include a slider which is relatively rotatably mounted with respect to the eccentric member. According to the construction described above, when the eccentric member is rotated, the diaphragm is moved in the radial direction of the output shaft while the slider is relatively rotated with respect to the eccentric member.

In accordance with an embodiment of the present invention, a pressure chamber may be provided which is closed by the diaphragm moved by the slider and is in communication with an inflow passage and an outflow passage, and a projecting part for moving the diaphragm is formed on an opposite side to the pressure chamber with respect to the diaphragm. According to the construction described above, when the pressure of the pressure chamber increases with the diaphragm being pushed by the slider through the projecting part, fluid flows out from the pressure chamber and, when the diaphragm is returned by the slider through the projecting part, the pressure of the pressure chamber decreases to make fluid flow into the pressure chamber.

According to the pump device described above in accordance with an embodiment of the present invention, since the cam mechanism makes the diaphragm move in the radial direction of the output shaft, the diaphragms are not required to be disposed on the same plane as the conventional example, and thus the downsizing of the pump device can be easily attained.

Further, when a stepping motor is used as the motor, the cam mechanism can be controlled by a little angle and thus a little flow rate can be obtained by means of operating only one pump at a time. As a result, the applicable scope of the pump device can be extended.

Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, various features of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:

FIGS. 1(A) and 1(B) are views showing a pump device in accordance with an embodiment of the present invention. FIG. 1(A) is a transverse cross-sectional front view of the pump device, and FIG. 1(B) is a longitudinal cross-sectional center view of the pump device.

FIG. 2 is an exploded perspective view showing a cam mechanism.

FIG. 3 is an exploded perspective view and a cross-sectional view showing a bearing holder and a contact ring.

FIG. 4 is a front view showing a contacting state of the contact ring with a diaphragm.

FIG. 5 is a plan view showing the case of a pump body.

FIG. 6 is a longitudinal cross-sectional center side view showing the pump body.

FIG. 7 is a bottom view showing the cover of the pump body.

FIG. 8 is a cross-sectional view showing a portion viewed from the arrows VIII-VIII in FIG. 7.

FIG. 9 is a side view showing the pump device.

FIG. 10 is a rear view showing the pump device.

FIG. 11 is a front view showing the pump device.

FIG. 12 is a cross-sectional view showing a flow passage cover.

FIG. 13 is a view showing a relationship between the cam mechanism and the diaphragm when the cam mechanism is rotated to 180 degrees.

FIG. 14 is a view showing a relationship between the displacement quantity of the diaphragm and the rotation angle of the cam mechanism in the respective pump bodies.

FIG. 15 is a view showing an operational example when the respective pump bodies are operated one by one.

FIG. 16 is a plan view showing a pump body in accordance with another embodiment of the present invention.

FIG. 17 is a longitudinal cross-sectional center side view showing a pump body in accordance with another embodiment of the present invention.

FIG. 18 is a longitudinal cross-sectional side view showing a diaphragm in accordance with another embodiment of the present invention.

FIG. 19 is a cross-sectional view showing a diaphragm in accordance with another embodiment of the present invention.

FIGS. 20(A), 20(B) and 20(C) are plan views showing embodiments in which different number of pump bodies are disposed. FIG. 20(A) shows an embodiment provided with one pump body, FIG. 20(B) with two pump bodies and FIG. 20(C) with three pump bodies.

FIGS. 21(A) and 21(B) are views showing a cam mechanism in accordance with another embodiment of the present invention. FIG. 21(A) is its front view and FIG. 21(B) is its side and partial cross-sectional view.

FIG. 22 is a transverse cross-sectional view showing a pump device in accordance with another embodiment of the present invention.

FIG. 23 is a longitudinal cross-sectional view showing the pump device in FIG. 22.

FIG. 24 is an exploded perspective view showing the pump device in FIG. 22.

FIG. 25 is a perspective view showing a cam mechanism in accordance with another embodiment of the present invention.

FIG. 26 is a longitudinal cross-sectional center side view showing a conventional pump device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Several embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

A pump device 1 in accordance with an embodiment of the present invention is shown in FIGS. 1 through 15. The pump device 1 includes a motor 2, an eccentric member 4 eccentrically mounted on the output shaft 3 of the motor 2, a cam mechanism 5 which engages with the eccentric member 4 for converting the turning or rotating motion of the eccentric member 4 into a motion in a radial direction of the output shaft 3, and pump bodies 7 through 10 each of which is provided with a diaphragm 6 for performing a pump operation that is moved in the radial direction of the output shaft 3 by the operation of the cam mechanism 5 as shown in FIGS. 1(A) and 1(B).

The motor 2 is a stepping motor. The motor 2 is mounted on a support plate 11 with a screw. The inner ring 22 of a ball bearing 12 is mounted on the eccentric member 4, for example, by press fitting. On the tip end of the output shaft 3 of the motor 2 are fixed a washer for pressing the ball bearing 12 and a slit ring 13 with a screw 14. The eccentric member 4 is fixed to the output shaft 3 of the motor 2 with a screw 49.

The cam mechanism 5 is provided with a slide guide 15 which is integrally formed on the support plate 11, a slider 16 which is slidable in a direction perpendicular to an axial direction (radial direction), and a bearing holder 17 for accommodating the ball bearing 12 as shown in FIG. 2. The slide guide 15 is formed in a ring shape around the output shaft 3 so as to protrude on the opposite side to the face of support plate 11 on which the motor 2 is mounted. At least two guide grooves 18 are formed on the end face of the slide guide 15 in the radial direction.

The slider 16 is formed in a ring shape and provided with slide guide side protruded parts 19 which are formed to protrude on the slide guide 15 side in the radial direction and bearing holder side protruded parts 20 which are formed to protrude on the bearing holder 17 side in the radial direction at different angular positions from those of the slide guide side protruded parts 19. The bearing holder 17 is formed in a cylindrical shape. On the end face on the slider 16 side are provided with guide grooves 21 formed in the radial direction with which the bearing holder side protruded parts 20 of the slider 16 are slidably engaged. The outer ring 23 of the ball bearing 12 is fitted to the bearing holder 17.

Further, as shown in FIG. 3, a contact ring 24 is rotatably mounted on the outer peripheral part of the bearing holder 17. Since the contact ring 24 is capable of rotating with respect to the bearing holder 17, as shown in FIG. 4, an impact at the time when the contact ring 24 abuts with the diaphragm 6 can be reduced by the relative rotation of the contact ring 24 with respect to the bearing holder 17. A concave groove 25 is formed on the outer peripheral face of the bearing holder 17 to which the contact ring 24 is fitted and a protruded part 26 fitting to the concave groove 25 is formed on the inner peripheral face of the contact ring 24. The concave groove 25 and the protruded part 26 are engaged with each other in a snap fitting manner and thus the contact ring 24 can be rotated and easily assembled through one-touch operation.

The pump bodies 7 through 10 are constructed in the same manner. Each of the pump bodies 7 through 10 is provided with a pressure chamber 28 constructed in a case 27 and a diaphragm 6 formed to close the pressure chamber 28 as shown in FIGS. 5 and 6. The materials used for the case 27 and the diaphragm 6 are those that do not react with a carrying fluid or a circulating fluid. A ring-shaped groove 29 is formed at the periphery of the aperture edge part of the pressure chamber 28. Further, a ring-shaped bead 30 is formed in the diaphragm 6. The diaphragm 6 is fixed to the case 27 by the bead 30 being pushed into the ring-shaped groove 29 and the aperture part of the pressure chamber 28 can be sealed up with the diaphragm 6. A sealing part 31 in a flat plate shape is continuously formed on the outer side of the bead 30 of the diaphragm 6. The sealing part 31 is sandwiched between the case 27 and the cover 32 and fixed with a screw, and thus the fixing of the diaphragm 6 and the sealing of the pressure chamber 28 can be firmly performed. The displacement dimension of the diaphragm 6 is set to be equal to or smaller than the eccentric dimension of the eccentric member 4. The displacement dimension of the diaphragm 6 can be changed by changing the eccentric dimension of the eccentric member 4.

A projecting part 33 is formed at the center of the opposite side face of the diaphragm 6 to the pressure chamber 28 for pressing and transforming the diaphragm 6. Fluorine coating is preferably applied on the projecting part 33 of the diaphragm 6 to enhance durability and reduce contact resistance. Alternatively, the projecting part 33 is covered with material having an abrasion resistance property and a low friction coefficient to enhance durability and reduce contact resistance.

An inflow passage 34 and an outflow passage 35 are formed in the pressure chamber 28 so as to be in communication with the outside. An L-shaped inflow valve groove 36 is formed on the way of the inflow passage 34 and an L-shaped inflow valve 37 is inserted into the inflow valve groove 36 and fixed. The inflow valve 37 has a mounting part 37 a and a valve part 37 b. The valve part 37 b is in tight contact with the opposite side face of the inflow valve groove 36 to the pressure chamber 28. Therefore, when the diaphragm is pushed and the pressure of the volume chamber increases, the fluid is flown out from the pressure chamber 28. At this time, the valve part 37 b is brought into tight contact with the wall of the inflow valve groove 36 and the flow is stopped. When the diaphragm is returned and the pressure of the volume chamber decreases, the fluid is flown into the pressure chamber 28. At this time, the valve part 37 b moves away from the wall of the inflow valve groove 36 and the fluid flows. In other words, the inflow valve 37 constructs a so-called check valve. A spot facing 39 for mounting an O-ring 38 is formed in the inlet port of the inflow passage 34.

An L-shaped outflow valve groove 40 is formed on the way of the outflow passage 35 and an L-shaped outflow valve 41 is inserted into the outflow valve groove 40 and fixed. The outflow valve 41 has a mounting part 41 a and a valve part 41 b. The valve part 41 b is in tight contact with the face of the outflow valve groove 40 on the pressure chamber 28 side. Therefore, when the diaphragm is returned and the pressure of the volume chamber decreases, the fluid is flown into the pressure chamber 28. At this time, the valve part 41 b is brought into tight contact with the wall of the outflow valve groove 40 and the flow is stopped. When the diaphragm is pushed and the pressure of the volume chamber increases, the fluid is flown out from the pressure chamber 28. At this time, the valve part 41 b moves away from the wall of the outflow valve groove 40 and the fluid flows. In other words, the outflow valve 41 constructs a so-called check valve. An outflow pipe 42 is connected to the outlet port of the outflow passage 35.

The respective valve parts 37 b, 41 b of the inflow valve 37 and the outflow valve 41 are formed of an extremely thin elastic member which is capable of being deformed with a prescribed little pressure. Thus, the valve can be operated with a small pressure loading. In addition, since a check valve structure is used which can be mounted only by inserting to the respective valve grooves 36, 40, a valve which is easily assembled with a high degree of sensibility and reliability can be obtained and the valve is capable of coping with a small flow rate.

As shown in FIGS. 7 and 8, the cover 32 is provided with a protruded part 51 (shown by the two-dot chain line in FIG. 7) at portions or positions which surround the inflow valve groove 36, the outflow valve groove 40 and the ring-shaped groove 29 shown in FIG. 5. The inflow valve groove 36, the outflow valve groove 40 and the ring-shaped groove 29 can be sealed by the protruded part 51 through the plate-shaped sealing part 31.

As shown in FIGS. 9 through 11, four pump bodies 7 through 10 are respectively arranged such that the cam mechanism 5 is located in its center. The projecting part 33 of the diaphragm 6 in each of the pump bodies 7 through 10 faces the contact ring 24 of the cam mechanism 5. In an embodiment of the present invention, the respective pump bodies 7 through 10 are disposed around the cam mechanism 5 at every 90 degrees with an equal distance. Further, the relationship of the respective pump bodies 7 through 10 and the cam mechanism 5 is arranged such that two of the pump bodies 7 through 10 are not simultaneously operated as shown in FIGS. 13 and 14. Therefore, since only one of the pump bodies 7 through 10 can be operated at a time, the output of a small flow rate can be obtained.

The outflow pipe 42 of each of the pump bodies 7 through 10 is penetrated through the through hole of the support plate 11 of the cam mechanism 5. An O-ring 38 is fitted to the spot facing 39 at the inlet port of each of the inflow passages 34. In addition, a flow passage cover 43 is provided on the side faces of the pump bodies 7 through 10 which are opposite to the cam mechanism 5. The flow passage cover 43 is provided with holes 44 each of which is formed at the position corresponding to the spot facing 39 of each of the pump bodies 7 through 10 and pipe lines 45 each of which is penetrated in its side face direction from the hole 44 as shown in FIG. 12. The pipe line 45 is protruded from the side face of the flow passage cover 43 and formed in a pipe shape so that another pipe can be easily connected with.

A circuit board 46 is disposed on the inner face side of the flow passage cover 43 as shown in FIG. 1. The circuit board 46 is provided with a photo interrupter 47 for detecting the rotation of a slit ring 13 that is mounted on the output shaft 3 and a drive circuit for the photo interrupter 47. Therefore, the rotating position of the output shaft 3 can be detected. The slit ring 13 is formed in a bowl shape having a flange portion which passes between a light emitting element and a light receiving element of the photo interrupter 47. Slits for detection are formed in the flange portion of the slit ring 13.

The operation of the above-mentioned pump device 1 will be described below.

When the motor 2 is driven, the inner ring 22 of the ball bearing 12 is rotated by the eccentric member 4. The outer ring 23 of the ball bearing 12 performs a circling movement with a radius of the eccentric dimension of the eccentric member 4. Accordingly, the bearing holder 17 and the contact ring 24 also perform a circling movement with the radius of the eccentric dimension of the eccentric member 4. Since the cam mechanism 5 is operated by the output shaft 3 through the eccentric member 4, the contact ring 24 performs a circling movement with the radius of the eccentric dimension of the eccentric member 4 which is fixed to the output shaft 3. Therefore, even though the contacting point of the contact ring 24 with the diaphragm is away from the rotation center, the contact speed “V” of the contact ring 24 with the diaphragm becomes very slow in comparison with the case when a rigid cam fixed to the rotating shaft is operated to directly move the diaphragm. As a result, the contact PV (product of pressure P and velocity V) can be extremely reduced in comparison with the case that the cam mechanism 5 is directly mounted on the output shaft 3, and thus the durability can be improved.

When the motor 2 is rotated, the contact ring 24 presses and then releases successively the projecting part 33 of the diaphragm 6 of each of the pump bodies 7 through 10 as shown in FIG. 13. In the respective pump bodies 7 through 10, the volume of the pressure chamber 28 is reduced by the diaphragm 6 being pressed and thus the inflow valve 37 is closed and simultaneously the outflow valve 41 is opened. Therefore, the fluid is pressed out from the pressure chamber 28. Further, the volume of the pressure chamber 28 is increased by the diaphragm 6 being released and thus the inflow valve 37 is opened and simultaneously the outflow valve 41 is closed. As a result, the fluid is drawn into the pressure chamber 28. The fluid is carried by the repetition of this operation.

The rotating position of the output shaft 3 is detected by the photo interrupter 47. Since the motor 2 is a stepping motor 2, the output shaft 3 can be rotated in movements of a specific or arbitrary angle with respect to each of the pump bodies 7 through 10. The movements of the diaphragms 6 in the respective pump bodies 7 through 10 do not simultaneously occur at two of the pump bodies as shown by the solid line in FIG. 14. Therefore, only one of the pump bodies can be operated at a time. In an embodiment of the present invention, the output shaft 3 can be operated such that the output shaft 3 is reciprocally rotated or turned in the range of 90 degrees as shown in FIG. 15. According to the construction described above, since the eccentric member 4 is reciprocated at every 90 degrees, only one of the pump bodies can be operated. At this time, the diaphragms 6 of other three pump bodies do not activate because they do not abut with the contact ring 24. For example, in the embodiment shown in FIG. 15, the pump body 7 is operated three times, then the pump body 8 is successively operated once, and then the pump body 9 is operated six times.

As described above, the motor 2 is a stepping motor. Therefore, normal or forward and reverse rotations are easily performed with a high degree of controllability and the accuracy of flow rate of the carried fluid can be enhanced by the pump device 1. Further, since the motor 2 is a stepping motor, the motor is not activated when operation is not required and thus an energy saving pump can be attained.

Although the present invention has been shown and described with reference to specific embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. For example, in an embodiment of the present invention, the diaphragm 6, the inflow valve 37 and the outflow valve 41 are formed in a separated manner. However, the present invention is not limited to this embodiment and they may be integrally formed as shown in FIGS. 16 and 17. For example, in an embodiment shown in FIGS. 16 and 17, the outflow valve 41 and the inflow valve 37 are integrally formed in the diaphragm 6 by cutting the diaphragm 6 in a U-shape. Further, in this embodiment of the present invention, the diaphragm 6 returns by itself when the diaphragm 6 is released from the contact ring 24. However, the present invention is not limited to this embodiment and a return spring 48 is disposed to make the diaphragm 6 return as shown in FIGS. 18 and 19. When the return spring 48 shown in FIG. 18 is used, it is necessary that the return spring 48 is made of material that is not eroded by the fluid because the return spring 48 comes into contact with the fluid.

In addition, in an embodiment of the present invention, the assembling of the respective pump bodies 7 through 10 is performed by using a screw, and further the assembling of the respective pump bodies 7 through 10 and the support plate 11 is also performed by using a screw. However, the present invention is not limited to this embodiment and ultrasonic, wave welding or adhesion may be used. Further, in an embodiment of the present invention, the photo interrupter 47 is used to detect the rotational position of the output shaft 3. However, the present invention is not limited to this embodiment and well-known rotation detecting means such as a Hall element or an MR (magneto-resistance effect) element may be used.

Further, in an embodiment of the present invention, four pump bodies 7 through 10 are provided. However, the present invention is not limited to this embodiment and, for example, the number of pump bodies may be set to be one through three as shown in FIGS. 20(A), 20(B) and 20(C), or set to be any arbitrary number. In this case, the displacement dimension of the diaphragm 6 can be sufficiently obtained with a smaller number of pump bodies. In addition, in an embodiment of the present invention, the pump bodies 7 through 10 are arranged to be constructed in only one stage in the axial direction of the output shaft 3. However, the present invention is not limited to this embodiment and a plurality of stages of the pump bodies may be arranged in the axial direction of the output shaft 3.

In an embodiment of the present invention, two types of free rotating members are arranged in the cam mechanism 5, in other words, the ball bearing 12 and the contact ring 24 are arranged in the cam mechanism 5. However, the present invention is not limited to this embodiment and the free rotating members are not necessarily provided in the cam mechanism 5. For example, the cam mechanism 5 comprising of a cam member as shown in FIGS. 21(A) and 21(1B) may be used. Further, a cam mechanism as shown in FIG. 25 may be used in which a roller 60 is rotatably mounted on a roller holder 61 where the roller 60 is eccentric to the output shaft 3 of the motor 2.

In addition, in an embodiment of the present invention, the bearing holder 17 presses the diaphragm 6 through the contact ring 24 by using the combination of the slide guide 15, the slider 16 and the bearing holder 17. However, the present invention is not limited to this embodiment and, instead of using the slide guide 15, the slider 16 and the bearing holder 17, a pair of sliders 50A, 50B may be arranged around the periphery of the ball bearing 12 such that the sliders 50A, 50B are engaged with the eccentric member 4 in the eccentric direction to reciprocate in a linear manner as shown in FIGS. 22 through 24. The diaphragms 6 are successively moved by the sliders 50A, 50B to perform pump operation. In this case, the sliders 50A, 50B are respectively engaged with the ball bearing 12 in the radial direction by fitting their central holes 54 to the outer race of the ball bearing 12. The head part of an engaging piece 53 provided at the center of the diaphragm 6 is engaged with a recessed part 52 provided in each of the sliders 50A, 50B so as to be disposed in one of two axes perpendicular to each other. The head parts of the engaging pieces 53 are respectively fitted into the recessed parts 52 of the slider 50A or 50 B such that the neck part of the engaging piece 53 is engaged with the flange 55 of the slider 50A or 50 B. Thereby, when the sliders 50A, 50B alternately move in the perpendicular directions to each other by the eccentric rotation of the eccentric member 4, the diaphragm 6 is pulled or pushed through the engaging piece 53 to contract or expand the pressure chamber 28. The sliders 50A, 50B are slidably supported only in the radial directions perpendicular to each other by means two straight grooves formed on the fixing member perpendicular to each other are engaged with plate-like protrusion parts of the sliders 50A, 50B, for example, by means of the groove 57 provided on the support cover 11 and the groove (not shown in the drawing) provided on the flow passage cover 43 are engaged with the protrusion parts 56. Therefore, when the motor 2 is rotated, the sliders 50A, 50B engaged with the ball bearing 12 move along the groove 57 by the eccentric motion of the eccentric member 4 to push and pull the diaphragms 6 to perform a function as a pump. The engaging piece 53 formed like a cover knob of a pan is fixed to a supporting plate 58 with a screw 59 so as to sandwich the diaphragm 6.

In an embodiment of the present invention, the diaphragm 6 is used. However, the present invention is not limited to this embodiment and a tube may be used.

While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 

1. A pump device comprising: a motor; an eccentric member which is mounted on an output shaft of the motor in an eccentric manner; a cam mechanism which is engaged with the eccentric member to convert a motion of the output shaft into a radial direction; and at least one pump body, which includes a diaphragm that is moved in the radial direction in relation to the output shaft by the cam mechanism for performing a pumping operation.
 2. The pump device according to claim 1, wherein the motor is a stepping motor.
 3. The pump device according to claim 1, wherein the cam mechanism includes a contact ring which is rotatably mounted with respect to the eccentric member and, when the eccentric member is rotated, the contact ring makes the diaphragm move in the radial direction relative to the output shaft while the contact ring relatively rotates with respect to the eccentric member.
 4. The pump device according to claim 1, further comprising: a pressure chamber which is closed by the diaphragm and is in communication with an inflow passage and an outflow passage; and a projecting part for moving the diaphragm which is formed on an opposite side to the pressure chamber with respect to the diaphragm, wherein, when the pressure of the pressure chamber increases with the diaphragm being pushed by the contact ring through the projecting part, fluid flows out from the pressure chamber and, when the diaphragm returns, the pressure of the pressure chamber decreases to make fluid flow into the pressure chamber.
 5. The pump device according to claim 4, wherein a fluorine coating is applied to the projecting part of the diaphragm.
 6. The pump device according to claim 4, wherein the projecting part of the diaphragm is covered with material having an abrasion resistance property and a low friction coefficient.
 7. The pump device according to claim 3, wherein the plurality of pump bodies are four pump bodies disposed around the cam mechanism at every 90 degrees with an equal distance, and only one of the four pump bodies is operated by the contact ring at a time.
 8. The pump device according to claim 1, further comprising a slider which is provided in the cam mechanism and relatively rotatably mounted with respect to the eccentric member, wherein, when the eccentric member is rotated, the diaphragm is moved in the radial direction of the output shaft while the slider is relatively rotated with respect to the eccentric member.
 9. The pump device according to claim 8, further comprising: a pressure chamber which is closed by the diaphragm and is in communication with an inflow passage and an outflow passage; and a projecting part for moving the diaphragm which is formed on an opposite side to the pressure chamber with respect to the diaphragm, wherein, when the pressure of the pressure chamber increases with the diaphragm being pushed by the slider through the projecting part, fluid flows out from the pressure chamber and, when the diaphragm is returned by the slider through the projecting part, the pressure of the pressure chamber decreases to make fluid flow into the pressure chamber.
 10. A pump device comprising: an eccentric member mounted on a output shaft; a cam mechanism which is engaged with the eccentric member to convert a motion of the output shaft into a radial direction; and at least one pump body comprising a diaphragm that is moved in the radial direction in relation to the output shaft by the cam mechanism for performing a pumping operation.
 11. The pump device according to claim 10, wherein the output shaft moves in discrete steps of rotation.
 12. The pump device according to claim 10 wherein the cam mechanism includes a contact ring which is rotatably mounted with respect to the eccentric member and is structured so that when the eccentric member is rotated, the contact ring makes the diaphragm move in the radial direction relative to the output shaft while the contact ring relatively rotates with respect to the eccentric member.
 13. The pump device according to claim 10, further comprising: a pressure chamber which is closed by the diaphragm and is in communication with an inflow passage and an outflow passage; and a projecting part for moving the diaphragm which is formed on an opposite side to the pressure chamber with respect to the diaphragm, wherein, when the pressure of the pressure chamber increases with the diaphragm being pushed by the contact ring through the projecting part, fluid flows out from the pressure chamber and, when the diaphragm returns, the pressure of the pressure chamber decreases to make fluid flow into the pressure chamber.
 14. The pump device according to claim 13, wherein a fluorine coating is applied to the projecting part of the diaphragm.
 15. The pump device according to claim 13, wherein the projecting part of the diaphragm is covered with material having an abrasion resistance property and a low friction coefficient.
 16. The pump device according to claim 12, wherein the plurality of pump bodies are four pump bodies disposed around the cam mechanism at every 90 degrees with an equal distance, and only one of the four pump bodies is operated by the contact ring at a time.
 17. The pump device according to claim 10, further comprising a slider which is provided in the cam mechanism and relatively rotatably mounted with respect to the eccentric member, wherein, when the eccentric member is rotated, the diaphragm is moved in the radial direction of the output shaft while the slider is relatively rotated with respect to the eccentric member.
 18. The pump device according to claim 15, further comprising: a pressure chamber which is closed by the diaphragm and is in communication with an inflow passage and an outflow passage; and a projecting part for moving the diaphragm which is formed on an opposite side to the pressure chamber with respect to the diaphragm, wherein, when the pressure of the pressure chamber increases with the diaphragm being pushed by the slider through the projecting part, fluid flows out from the pressure chamber and, when the diaphragm is returned by the slider through the projecting part, the pressure of the pressure chamber decreases to make fluid flow into the pressure chamber. 